Virgolini I, Li S, Sillaber C, Majdic O, Sinzinger H, Lechner K, Bettelheim P, Valent P
Department of Nuclear Medicine, University of Vienna, Austria.
J Biol Chem. 1992 Jun 25;267(18):12700-8.
Recent data suggest that prostaglandins (PGs) are involved in the regulation of basophil activation. The aim of this study was to characterize the basophil PG-binding sites by means of radioreceptor assays using 3H-labeled PGs. Scatchard analysis for pure (greater than 95%) chronic myeloid leukemia (CML) basophils revealed two classes of PGE1-binding sites differing in their affinity for the natural ligand (Bmax1 = 217 +/- 65 fmol/10(8) cells; Kd1 = 0.5 +/- 0.2 nM; Bmax2 = 2462 +/- 381 fmol/10(8) cells; Kd2 = 47 +/- 20 nM; IC50 = PGE1 less than PGI2 less than PGD2 less than PGE2 less than PGF2 alpha) as well as two classes of PGI2 (iloprost)-binding sites (Bmax1 = 324 +/- 145 fmol/10(8) cells; Kd1 = 0.5 +/- 0.3 nM; Bmax2 = 2541 +/- 381; Kd2 = 27 +/- 6 nM; IC50 = PGI2 less than PGE1 less than PGD2 less than PGE2 less than PGF2 alpha. In addition, CML basophils exhibited a single class of PGD2-binding sites (Bmax = 378 +/- 98 fmol/10(8) cells; Kd = 13 +/- 4 nM; IC50: PGD2 less than PGI2 less than PGE1 less than PGE2 less than PGF2 alpha). In contrast, we were unable to detect specific saturable PGE2-binding sites. Primary and immortalized (KU812) CML basophils revealed an identical pattern of PG receptor expression. Basophils (KU812) expressed significantly (p less than 0.001) lower number of PGE1 (PGI2)-binding sites (Bmax1: 9% (20%) of control; Bmax2: 36% (50%) of control) when cultured with recombinant interleukin 3 (rhIL-3), a basophil-activating cytokine, whereas rhIL-2 had no effect on PG receptor expression. Functional significance of binding of PGs to basophils was provided by the demonstration of a dose-dependent increase in cellular cAMP upon agonist activation, with PGE1 (ED50 = 1.7 +/- 1.1 nM) and PGI2 (ED50 = 2.8 +/- 2.3 nM) being the most potent compounds. These findings suggest that human basophils express specific receptors for PGE1, PGI2 as well as for PGD2.
近期数据表明，前列腺素（PGs）参与嗜碱性粒细胞激活的调节。本研究的目的是通过使用3H标记的PGs的放射受体分析来表征嗜碱性粒细胞PG结合位点。对纯的（>95%）慢性髓性白血病（CML）嗜碱性粒细胞进行Scatchard分析，发现两类PGE1结合位点对天然配体的亲和力不同（Bmax1 = 217 ± 65 fmol/10(8)细胞；Kd1 = 0.5 ± 0.2 nM；Bmax2 = 2462 ± 381 fmol/10(8)细胞；Kd2 = 47 ± 20 nM；IC50 = PGE1 < PGI2 < PGD2 < PGE2 < PGF2α），以及两类PGI2（依洛前列素）结合位点（Bmax1 = 324 ± 145 fmol/10(8)细胞；Kd1 = 0.5 ± 0.3 nM；Bmax2 = 2541 ± 381；Kd2 = 27 ± 6 nM；IC50 = PGI2 < PGE1 < PGD2 < PGE2 < PGF2α）。此外，CML嗜碱性粒细胞表现出一类PGD2结合位点（Bmax = 378 ± 98 fmol/10(8)细胞；Kd = 13 ± 4 nM；IC50：PGD2 < PGI2 < PGE1 < PGE2 < PGF2α）。相比之下，我们未能检测到特异性的可饱和PGE2结合位点。原发性和永生化（KU812）CML嗜碱性粒细胞显示出相同的PG受体表达模式。当与嗜碱性粒细胞激活细胞因子重组白细胞介素3（rhIL-3）一起培养时，嗜碱性粒细胞（KU812）表达的PGE1（PGI2）结合位点数量显著减少（p < 0.001）（Bmax1：对照组的9%（20%）；Bmax2：对照组的36%（50%）），而rhIL-2对PG受体表达没有影响。通过激动剂激活后细胞内cAMP呈剂量依赖性增加证明了PGs与嗜碱性粒细胞结合的功能意义，其中PGE1（ED50 = 1.7 ± 1.1 nM）和PGI2（ED50 = 2.8 ± 2.3 nM）是最有效的化合物。这些发现表明，人嗜碱性粒细胞表达PGE1、PGI2以及PGD2的特异性受体。
